1. Field of the Invention
The present invention relates to a waterproof casing for containing electronic components, the casing including a respiration filter.
2. Description of Related Art
An example of a waterproof casing for containing electronic components therein is disclosed in JP-A-2002-134939. This casing is composed of a case body and a bottom cover for covering a bottom opening of the case body. A depressed portion is formed on an upper surface of the case body, and a tube for establishing communication between an inner space of the casing and an outside of the casing is disposed in the depressed portion. An upper opening of the tube is covered with a respiration filter. A drain groove is formed in the depressed portion to drain water entered into the depressed portion to a side opening of the casing.
However, there is a problem in the casing, that water closes respiration holes of the filter by its surface tension before it reaches the side opening of the casing when the casing takes a position where the drain groove becomes horizontal. This makes respiration of the casing difficult.